Pfizer recently announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to the company’s investigational antibody-drug conjugate inotuzumab ozogamicin for acute lymphoblastic leukemia (ALL). The FDA’s decision was based on the results of the phase III INO-VATE ALL trial, which enrolled 326 adult patients with relapsed or refractory CD22-positive ALL and compared inotuzumab ozogamicin to standard-of-care chemotherapy. Efficacy and safety results from the trial were announced in April 2015 and presented at the 20th Congress of the European Hematology Association in Vienna.1

Inotuzumab ozogamicin is an investigational antibody-drug conjugate comprised of a monoclonal antibody targeting CD22, a cell-surface antigen expressed on approximately 90% of B-cell malignancies, linked to a cytotoxic agent. When inotuzumab ozogamicin binds to the CD22 antigen on malignant B cells, it is internalized into the cell, where the cytotoxin calicheamicin is released to destroy the cell.

Mace Rothenberg, MD, Senior Vice President of Clinical Development and Medical Affairs and Chief Medical Officer for Pfizer Oncology, said in a press release “Breakthrough therapy designation will allow us to work more closely with the FDA to bring this important therapy to patients as rapidly as possible.” ■